title: [Serologic response measured by complement fixation in children with acute respiratory infection].
abstract: The aim of this work was to evaluate the sensitivity of complement fixation for serological diagnosis of lower acute respiratory infections (ARI) in small children in comparison with direct methods such as indirect immunofluorescence (IIF) on nasopharyngeal aspirate and tissue culture isolation. Sera from children under 5 year of age with ARI were studied by complement fixation for 6 respiratory viruses (respiratory syncytial virus (RSV), adenovirus, influenza A and B and parainfluenza 1 and 3). In all, 264 pairs of serum samples from children with viral ARI diagnosis (n:135) or from doubtful cases (n:90) were studied. Thirty nine sera were anticomplementary. In samples from confirmed viral ARI patients, seroconversion was detected in 38%, whereas from those with a doubtful diagnosis it was only 14%. Seroconversion for RSV and adenovirus was 39% and 50%, respectively. On correlating seroconversion for the 6 viruses according to age group, 20% positivity was found in the 0-5 month-old group, 35% in the 6-10 month-old and 30% in those over 11 months of age. For RSV alone, 0-5 month-old patients presented 25% seroconversion, and in those over 6 months of age the percentage exceeded 60% (p less than 0.001). Complement fixation test sensitivity vs direct methods (IIF and/or culture) was 38.5%). Our findings confirm the low sensitivity of complement fixation to detect antibodies in ARI, particularly in children under 6 months of age and support the higher efficacy of direct diagnostic methods. However, complement fixation serology is useful for epidemiological studies in children over 6 months of age, since over 60% of RSV were readily detected.
authors.affiliation: Departamento de Microbiología, FAcultad de Medicina, Universidad de Buenos Aires, Argentina.
authors.forename: B
authors.initials: B
authors.lastname: Ebekian
authors.forename: G
authors.initials: G
authors.lastname: Carballal
authors.forename: C
authors.initials: C
authors.lastname: Cerqueiro
authors.forename: M
authors.initials: M
authors.lastname: Avila
authors.forename: H
authors.initials: H
authors.lastname: Salomón
authors.forename: M
authors.initials: M
authors.lastname: Weissenbacher
mesh_terms: D002675:Child, Preschool; D003168:Complement Fixation Tests; D005455:Fluorescent Antibody Technique; D006801:Humans; D007223:Infant; D012141:Respiratory Tract Infections / Q000097:blood* / Q000276:immunology / Q000382:microbiology; D014776:Virus Cultivation; D014777:Virus Diseases / Q000097:blood*; D014780:Viruses / Q000302:isolation & purification
vernacular_title: Respuesta serológica medida por fijación de complemento en niños con infección respiratoria aguda.